Answer:
(Choice A) Only those viewers who called in
Explanation:
The statement tell us Ninety percent of the viewers that call in say that they will vote against the tax increase.
This explains it is option A .
Choice B is incorrect as all viewers may not have called in.
Choice C is also incorrect all regular viewers do not call in.
Choice D is incorrect calls are not received at any point at only specific time.
Choice E is incorrect because all voters again may not call in.